Let's do this one at a time.
Smelt Touch: Ah yes, the "insta-smelt" enchantment, a favourite of mods. Personally on the edge; my main objection is that it'd make furnaces, and especially blast furnaces, redundant in the late-game.
Unburning: I think this should instead be a default property of all tools from iron up.
Critical: No objections.
Reinforcement: I'd like to see this, but not as an enchantment. Possibly as a default for all tools, or applied with a certain item.
Wrecking: No objections.
Overshot: Support the idea, but the current levels are too OP; I'd suggest +25% per level.
Fire Strider and Lava Affinity: I don't think you're meant to swim in lava.
Multishot Changes: Too OP.
Curse enchantments: Unsure.
New block: This could potentially be applied to the grindstone, given that it is used to disenchant objects.